1. Technical Field
Various exemplary embodiments relate to a data storage device, and more particularly, to a data storage device capable of effectively performing a merge operation, an operation method thereof, and a data processing system including the same.
2. Related Art
The recent paradigm for computer surroundings has changed into ubiquitous computing environments in which computer systems may be used anytime and anywhere. Thus, the use of portable electronic devices such as mobile phones, digital cameras, and notebook computers has rapidly increased. Such portable electronic devices generally employ a data storage device using a memory device. The data storage device is used as a main memory device or auxiliary memory device of the portable electronic devices.
Since the data storage device using a memory device has no mechanical driver, the data storage device has excellent stability and durability. Furthermore, the data storage device has high access speed and small power consumption. The data storage device having such advantages includes a universal serial bus (USB) memory device, a memory card having various interfaces, and a solid state drive (SSD).
As portable electronic devices play a large file such as music file and video file, the data storage device is required to have a large storage capacity. The data storage device includes a memory device having a high integration degree for memory cells to secure a large storage capacity, for example, a flash memory device, which is one of nonvolatile memory devices.
The flash memory device does not support an overwrite operation due to structural characteristics thereof. That is, the flash memory device may not update data of a programmed memory cell. Thus, an erase operation must be preceded in order to program data to the flash memory device. This operation is referred to as an erase-before-program operation. That is, a programmed memory cell of the flash memory device must be returned to an initial state or erase state before data is programmed.
However, the erase operation of the flash memory device requires a long time. For this reason, after erasing a programmed memory cell, a controller to control the flash memory device in the data storage device does not program data to the erased memory cell. Instead, the controller programs data, which is to be written to the programmed memory cell, to another memory cell returned to an erase state.
For this operation of the controller, memory cells of the flash memory device may store both of valid data and invalid data. Depending on cases, the controller performs a merge operation of collecting valid data in one space and erasing invalid data.